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Section Information

Learmonth Type II Tool

The display consists of the current real time Learmonth Spectrograph image
with a row of three buttons at the top of the image, "clear", "compute speed" and "fundamental".

Selecting shock type

The shock type can be selected by clicking on the button labelled "fundamental"
(default) located at the top of the display. A two item drop down menu
appears, and shock type (fundamanetal or harmonic) can be selected by using
the left mouse button. The shock type should be selected before entering
the shock points.

Entering shock points

To enter shock points for speed computation click along the shock in
the image at several points from top left to bottom right. Each point
clicked is marked by the frequency (F) at that point and the number of
seconds (S) from the first point clicked. The "Newkirk" model used for conversion
from frequency to altitude in the solar atmosphere has an upper frequency limit of
540 MHz if harmonic is chosen and a limit of 280 MHz if fundamental
is chosen. Points clicked above these limits will not be displayed.

Computing shock speed

To compute shock speed click on the button labeled "compute speed". The
result is displayed top right of the image.

Clearing input

The "clear" button clears all input data.

Also, when using this tool it is important to note that there are no
time discontinuities in the data image.

Why is it done?

Type II radio burst shock speeds can give an indication of the travel time of a
coronal mass ejection from the Sun to the Earth.

You can also select hour images from the current day from the drop down list at the top of the display.